Re-Calibrating the machine?

Hi all! I am fairly new (less then a year) to all this and own a Shapeoko XXL. I have been going along and everything seems fine. However, this past weekend I started a project that has some fairly tight tolerances, an award plaque with lettering near the edge. I ran it and noticed that the lettering was going too far. So I scrapped it and tried again. This time I made sure the material was the exact dimensions, 11.25 inches, but when I manually jog the machine from zero up the y axis 11.25 inches, it goes off the material about .1 inch.

I thought that was weird so I tried the circle/diamond/square test to see how calibrated the machine was and it turned out great.

Square-3.99 inches and was supposed to be 4 inches
Diamond- 2.49 inches and was supposed to be 2.5 inches
Circle- 2 inches exactly

Any ideas?

Have you calibrated for belt stretch per:

First though, check and see if you need new belts we’ll cover them under warranty — if you have steel core even if you’re out of warranty contact

Yeah, just did that as well. my cheap calipers seem to think that it’s good, well about 149mm and not 150 but I think that’s because of the way the calipers fit into the Vbit holes.

You should be cutting the holes so that it’s the caliper tips which determine how the holes are measured and nothing else.

Yep, I made the holes too big and the calipers were kind of weird in them. However, I feel fairly confident in the results. Even if it was 1 mm off over 150, I don’t think that translates into .15 inches over 11.25 inches. But I think I will try it again tomorrow. Sometimes stepping away from the problem for a while helps.

That’s still quit a bit out. .015 = 3.8mm. The machine should easily be able to maintain < .005" over 16"
2mm over twelve inches is still well above that.

@gonziago Exactly how are you zeroing XY?
Is the CENTER of your endmill directly over the edge of the stock?


Yep, I was zeroing using a 60 degree Vbit and it was right over the corner. I kind of fudged the math for this one. Made the design just a bit smaller and zero’ed a bit low. So there was some error both below and above, however because the design was smaller it still all fit on the piece. Not the greatest resolution, but I was able to finish and will continue to work on the machine this weekend.

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